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Updated: Jul 15, 2026
A General Method for Evaluating Deep Brain Stimulation Effects on Intravenous Methamphetamine Self-Administration
Published on: January 22, 2016
Escalating dose, multiple binge methamphetamine regimen does not impair recognition memory in rats
Robert E Clark1, Ronald Kuczenski, David S Segal
1Veterans Affairs Medical Center, San Diego, California, USA. reclark@ucsd.edu
Abstract:
Rats exposed to methamphetamine (METH) in an acute high dose "binge" pattern have been reported to exhibit a persistent deficit in a novel object recognition (NOR) task, which may suggest a potential risk for human METH abusers. However, most high dose METH abusers initially use lower doses before progressively increasing the dose, only eventually engaging in multiple daily administrations. To simulate this pattern of METH exposure, we administered progressively increasing doses of METH to rats over a 14 day interval, then treated them with daily METH binges for 11 days. This treatment resulted in a persistent deficit in striatal dopamine (DA) levels of approximately 20%. We then tested them in a NOR task under a variety of conditions. We could not detect a deficit in their performance in the NOR task under any of the testing conditions. These results suggest that mechanisms other than or additional to the decrement in striatal DA associated with an acute METH binge are responsible for the deficit in the NOR task, and that neuroadaptations consequential to prolonged escalating dose METH pretreatment mitigate against these mechanisms.
Insights
Methamphetamine (METH) binge exposure in rats did not impair novel object recognition (NOR) after prolonged escalating dose pretreatment. Neuroadaptations may protect against METH-induced cognitive deficits.
Area of Science:
- Neuroscience
- Pharmacology
- Toxicology
Background:
- Acute high-dose methamphetamine (METH) binges can cause persistent cognitive deficits in rats, specifically in novel object recognition (NOR).
- Human METH abuse often involves a pattern of progressively increasing doses, not just acute high-dose binges.
Purpose of the Study:
- To investigate the effects of a simulated human METH abuse pattern (escalating doses followed by binges) on NOR performance in rats.
- To determine if neuroadaptations from this exposure pattern alter METH's impact on striatal dopamine (DA) and cognitive function.
Main Methods:
- Rats received escalating METH doses over 14 days, followed by 11 days of METH binges.
- Striatal DA levels were measured post-treatment.
- Rats were tested on the NOR task under various conditions.
Main Results:
- The METH exposure regimen induced a persistent ~20% deficit in striatal DA levels.
- Despite reduced DA, rats did not exhibit deficits in the NOR task under any tested conditions.
- This suggests that the DA deficit alone does not cause NOR impairment in this model.
Conclusions:
- Prolonged, escalating METH exposure followed by binges does not lead to NOR deficits, unlike acute high-dose binges.
- Neuroadaptations resulting from the escalating dose pretreatment may mitigate the cognitive impairments typically associated with METH-induced DA reduction.
- Mechanisms underlying NOR deficits likely involve factors beyond striatal DA depletion, and these are counteracted by prior METH exposure patterns.
